Thermal and Elastic Properties of Cu-Hf-Al Bulk Metallic Glasses

Abstract

Stable bulk glass forming alloys can be developed over a wide range of compositions in the Cu-Hf-Al ternary system. The compositional and the cooling rate dependences of the thermal and the elastic properties of Cu-Hf-Al alloys were systematically investigated. Evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The glass transition temperature (T-g) and crystallization temperature (T-x) were obtained for the alloys by using differential scanning calorimetry (DSC) at a heating rate of 20 K/min. In the results, the differences between the glass temperature and the crystallization temperature (Delta T-x = T-x - T-g) were measured to have values ranging up to 72 - 74 K. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson's ratio are also given.